Earlier quoted context omitted.
This has been a long standing problem of my own. I think finding a true co-founder if you don't already have someone immediately present in your pool is extraordinarily difficult. The sub-optimal thing is especially difficult if you've already started (I'm 8 months in myself), and then it doesn't make sense to divide equity equally any more either, so you effectively end up with a "first employee" rather than a true…
I have a suspicion that with the rise of YC, at least for a time, there were people searching for a cargo cult co founder. Not someone who meets all the requirements you describe, but a co-founder for the sake of having one because PG said so.
Actually, the breaking point was when the "co-founder" I found told me on the day after I arrived in Berlin to work on the project full time that he wouldn't be able to join in. In this case, he had a totally legit reason (his wife was in the hospital with cancer), but it was probably the case that aligning things as far as a "co-founder" was never necessary from the beginning. Either way, it was a bit catastrophic mentally for me for a couple weeks, toying with merging with a different startup in the same space instead of going full stop ahead on my own. Even now loneliness sometimes takes its toll.
Thankfully, in the end I spent a lot more time on product than worrying about finding a new co-founder, and we have a pretty d* good product now and 30% growth across our KPIs for the last two months. Not really a lot of cash in the bank account, but hell, this is Europe and investors like to sit on their money instead of invest it.